Several applications that involve the thermal processing of substrates such as semiconductor wafers and other materials involve the process steps of rapidly heating and cooling a substrate. One example of such processing is rapid thermal processing (RTP), which is used for a number of semiconductor fabrication processes.
Rapid thermal processing (RTP) radiate heat energy from lamps into the process chamber and onto a semiconductor substrate in the processing chamber. In this manner, the wafer is heated to a required processing temperature. During semiconductor processing operations, the lamps operate at extremely high temperatures. Not all of the heat energy provided by the RTP chamber lamps end up actually heating the wafer. Some of the radiant energy is absorbed by chamber components, especially the reflective components in the radiation field. This is particularly true for emitted energy from point sources which emit light in all directions.
In addition, in the semiconductor industry, it is often desirable to obtain temperature uniformity in the substrate during temperature cycling of substrate. Temperature uniformity provides uniform process variables on the substrate (e.g. layer thickness, resistivity, etch depth) for temperature activated steps such as film deposition, oxide growth, and etching. Furthermore, temperature uniformity in the substrate is necessary to prevent thermal stress-induced substrate damage such as warpage, defect generation, and substrate slip.
Accordingly, the inventors have provided improved heat energy sources, reflectors, and reflector materials for improved reflection of radiation for semiconductor substrate processing.